摘要
本論文主要為設計製作一中空圓柱型霧化器，藉由產生大振幅之機制來達到超音波霧化，並以滿足霧滴直徑小於30微米之精密塗佈效應(droplet effect)為目標。在中空圓柱型壓電材料貼附於金屬管上，將整體結構前後兩端點固定，經選擇適當之振動模態可在管近中央處產生最大振幅變形，而該處設計微小孔徑作為管內流體流出口而隨即霧化，可於該處產生液滴塗佈之效果。 本文利用有限元素分析軟體ANSYS來進行模態分析，找出中空圓柱型霧化器共振模態、頻率響應，作為驅動源的設計參考依據。本研究亦架設一套霧化量測系統，包括微液滴影像觀測原理、中空圓柱型霧化器、夾固平台、影像處理四部分，利用高速攝影機所拍攝霧化影像搭配分析軟體imageJ即可得到顆粒大小及粒徑分佈。實驗使用液體為水，經實驗液體為水驗證依目前設計之中空圓柱型霧化器其操作頻率為45.3kHz振幅大於6.8μm，可產生霧化現象，且發現當頻率固定時振幅與平均粒徑關係成正比。經測量之霧化顆粒大小及均勻度及分佈性發現在振幅為6.8μm時平均粒徑28.3μm，然而振幅加大至9μm時平均粒徑為34μm，其原因為加大振幅容易產生較大液滴。且由粒徑分佈圖可看出6.8μm之粒徑大小多集中於30μm，均勻度及分佈性較佳，而振幅加大至9μm時會產生40~50μm之較大粒徑，其均勻度及分佈性較差。
並列摘要
Motivation of this thesis is to design a cylindrical hollow atomizer. The purpose is produce ultrasonic atomization and to meet the target of droplet size less than 30 microns for precision coating by means of generating large amplitude. A disk-type piezoelectric actuator is attached to a hollow metal tube. The entire structure is fixed at both two end points. By choosing desired mode shape which can generate maximum deformation near the middle of the metal tube where a small hole allows fluid to flow out from the tube, atomization will occur at the surface around the hole. Finite element method by using ANSYS is carried out to accomplish modal analysis and harmonic analysis of the atomizer. A set of atomization measurement system is built including high-speed camera and imaging processing by use of ImageJ software that can provide the information of particle size and distribution. Considering of application of the actuator, a variety measurement of amplitude is carried out,and carried out particle size measurement of the hollow cylindrical atomizer, experimental liquid is water, we using high-speed cameras and analysis software ImageJ to get information about the particle size and the distribution of data. Water is used for experimental testing. While drives the hollow tube with operating frequency of 45.3kHz and the maximum amplitude is great than 6.8μm, atomization occurs with average particle diameter of 28.3μm and obtains good uniformity and distribution. However, while increases amplitude up to 9μm, atomization occurs with average particle diameter of 34μm due to large amplitude producing larger particle size. Also, the uniformity and distribution becomes worse.